/*
 * Copyright (C) 2011 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.collect;

import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtIncompatible;
import java.util.NoSuchElementException;
import java.util.Set;
import javax.annotation.Nullable;

/**
 * A set comprising zero or more {@linkplain Range#isEmpty nonempty},
 * {@linkplain Range#isConnected(Range) disconnected} ranges of type {@code C}.
 *
 * <p>
 * Implementations that choose to support the {@link #add(Range)} operation are required to ignore
 * empty ranges and coalesce connected ranges. For example:
 * 
 * <pre>
 *    {@code
 *
 *   RangeSet<Integer> rangeSet = TreeRangeSet.create();
 *   rangeSet.add(Range.closed(1, 10)); // {[1, 10]}
 *   rangeSet.add(Range.closedOpen(11, 15)); // disconnected range; {[1, 10], [11, 15)}
 *   rangeSet.add(Range.closedOpen(15, 20)); // connected range; {[1, 10], [11, 20)}
 *   rangeSet.add(Range.openClosed(0, 0)); // empty range; {[1, 10], [11, 20)}
 *   rangeSet.remove(Range.open(5, 10)); // splits [1, 10]; {[1, 5], [10, 10], [11, 20)}}
 * </pre>
 *
 * <p>
 * Note that the behavior of {@link Range#isEmpty()} and {@link Range#isConnected(Range)} may not be
 * as expected on discrete ranges. See the Javadoc of those methods for details.
 *
 * <p>
 * For a {@link Set} whose contents are specified by a {@link Range}, see {@link ContiguousSet}.
 *
 * <p>
 * See the Guava User Guide article on
 * <a href= "https://github.com/google/guava/wiki/NewCollectionTypesExplained#rangeset">
 * RangeSets</a>.
 *
 * @author Kevin Bourrillion
 * @author Louis Wasserman
 * @since 14.0
 */
@Beta
@GwtIncompatible
public interface RangeSet<C extends Comparable> {
    // TODO(lowasser): consider adding default implementations of some of these methods

    // Query methods

    /** Determines whether any of this range set's member ranges contains {@code value}. */
    boolean contains(C value);

    /**
     * Returns the unique range from this range set that {@linkplain Range#contains contains}
     * {@code value}, or {@code null} if this range set does not contain {@code value}.
     */
    Range<C> rangeContaining(C value);

    /**
     * Returns {@code true} if there exists a non-empty range enclosed by both a member range in
     * this range set and the specified range. This is equivalent to calling
     * {@code subRangeSet(otherRange)} and testing whether the resulting range set is non-empty.
     *
     * @since 20.0
     */
    boolean intersects(Range<C> otherRange);

    /**
     * Returns {@code true} if there exists a member range in this range set which
     * {@linkplain Range#encloses encloses} the specified range.
     */
    boolean encloses(Range<C> otherRange);

    /**
     * Returns {@code true} if for each member range in {@code other} there exists a member range in
     * this range set which {@linkplain Range#encloses encloses} it. It follows that
     * {@code this.contains(value)} whenever {@code other.contains(value)}. Returns {@code true} if
     * {@code other} is empty.
     *
     * <p>
     * This is equivalent to checking if this range set {@link #encloses} each of the ranges in
     * {@code other}.
     */
    boolean enclosesAll(RangeSet<C> other);

    /**
     * Returns {@code true} if for each range in {@code other} there exists a member range in this
     * range set which {@linkplain Range#encloses encloses} it. Returns {@code true} if
     * {@code other} is empty.
     *
     * <p>
     * This is equivalent to checking if this range set {@link #encloses} each range in {@code
     * other}.
     *
     * @since 21.0
     */
    default boolean enclosesAll(Iterable<Range<C>> other) {
        for (Range<C> range : other) {
            if (!encloses(range)) {
                return false;
            }
        }
        return true;
    }

    /**
     * Returns {@code true} if this range set contains no ranges.
     */
    boolean isEmpty();

    /**
     * Returns the minimal range which {@linkplain Range#encloses(Range) encloses} all ranges in
     * this range set.
     *
     * @throws NoSuchElementException if this range set is {@linkplain #isEmpty() empty}
     */
    Range<C> span();

    // Views

    /**
     * Returns a view of the {@linkplain Range#isConnected disconnected} ranges that make up this
     * range set. The returned set may be empty. The iterators returned by its
     * {@link Iterable#iterator} method return the ranges in increasing order of lower bound
     * (equivalently, of upper bound).
     */
    Set<Range<C>> asRanges();

    /**
     * Returns a descending view of the {@linkplain Range#isConnected disconnected} ranges that make
     * up this range set. The returned set may be empty. The iterators returned by its
     * {@link Iterable#iterator} method return the ranges in decreasing order of lower bound
     * (equivalently, of upper bound).
     *
     * @since 19.0
     */
    Set<Range<C>> asDescendingSetOfRanges();

    /**
     * Returns a view of the complement of this {@code RangeSet}.
     *
     * <p>
     * The returned view supports the {@link #add} operation if this {@code RangeSet} supports
     * {@link #remove}, and vice versa.
     */
    RangeSet<C> complement();

    /**
     * Returns a view of the intersection of this {@code RangeSet} with the specified range.
     *
     * <p>
     * The returned view supports all optional operations supported by this {@code RangeSet}, with
     * the caveat that an {@link IllegalArgumentException} is thrown on an attempt to
     * {@linkplain #add(Range) add} any range not {@linkplain Range#encloses(Range) enclosed} by
     * {@code view}.
     */
    RangeSet<C> subRangeSet(Range<C> view);

    // Modification

    /**
     * Adds the specified range to this {@code RangeSet} (optional operation). That is, for equal
     * range sets a and b, the result of {@code a.add(range)} is that {@code a} will be the minimal
     * range set for which both {@code a.enclosesAll(b)} and {@code a.encloses(range)}.
     *
     * <p>
     * Note that {@code range} will be {@linkplain Range#span(Range) coalesced} with any ranges in
     * the range set that are {@linkplain Range#isConnected(Range) connected} with it. Moreover, if
     * {@code range} is empty, this is a no-op.
     *
     * @throws UnsupportedOperationException if this range set does not support the {@code add}
     *         operation
     */
    void add(Range<C> range);

    /**
     * Removes the specified range from this {@code RangeSet} (optional operation). After this
     * operation, if {@code range.contains(c)}, {@code this.contains(c)} will return {@code false}.
     *
     * <p>
     * If {@code range} is empty, this is a no-op.
     *
     * @throws UnsupportedOperationException if this range set does not support the {@code remove}
     *         operation
     */
    void remove(Range<C> range);

    /**
     * Removes all ranges from this {@code RangeSet} (optional operation). After this operation,
     * {@code this.contains(c)} will return false for all {@code c}.
     *
     * <p>
     * This is equivalent to {@code remove(Range.all())}.
     *
     * @throws UnsupportedOperationException if this range set does not support the {@code clear}
     *         operation
     */
    void clear();

    /**
     * Adds all of the ranges from the specified range set to this range set (optional operation).
     * After this operation, this range set is the minimal range set that
     * {@linkplain #enclosesAll(RangeSet) encloses} both the original range set and {@code other}.
     *
     * <p>
     * This is equivalent to calling {@link #add} on each of the ranges in {@code other} in turn.
     *
     * @throws UnsupportedOperationException if this range set does not support the {@code addAll}
     *         operation
     */
    void addAll(RangeSet<C> other);

    /**
     * Adds all of the specified ranges to this range set (optional operation). After this
     * operation, this range set is the minimal range set that {@linkplain #enclosesAll(RangeSet)
     * encloses} both the original range set and each range in {@code other}.
     *
     * <p>
     * This is equivalent to calling {@link #add} on each of the ranges in {@code other} in turn.
     *
     * @throws UnsupportedOperationException if this range set does not support the {@code addAll}
     *         operation
     * @since 21.0
     */
    default void addAll(Iterable<Range<C>> ranges) {
        for (Range<C> range : ranges) {
            add(range);
        }
    }

    /**
     * Removes all of the ranges from the specified range set from this range set (optional
     * operation). After this operation, if {@code other.contains(c)}, {@code this.contains(c)} will
     * return {@code false}.
     *
     * <p>
     * This is equivalent to calling {@link #remove} on each of the ranges in {@code other} in turn.
     *
     * @throws UnsupportedOperationException if this range set does not support the
     *         {@code removeAll} operation
     */
    void removeAll(RangeSet<C> other);

    /**
     * Removes all of the specified ranges from this range set (optional operation).
     *
     * <p>
     * This is equivalent to calling {@link #remove} on each of the ranges in {@code other} in turn.
     *
     * @throws UnsupportedOperationException if this range set does not support the
     *         {@code removeAll} operation
     * @since 21.0
     */
    default void removeAll(Iterable<Range<C>> ranges) {
        for (Range<C> range : ranges) {
            remove(range);
        }
    }

    // Object methods

    /**
     * Returns {@code true} if {@code obj} is another {@code RangeSet} that contains the same ranges
     * according to {@link Range#equals(Object)}.
     */
    @Override
    boolean equals(@Nullable Object obj);

    /**
     * Returns {@code asRanges().hashCode()}.
     */
    @Override
    int hashCode();

    /**
     * Returns a readable string representation of this range set. For example, if this
     * {@code RangeSet} consisted of {@code Range.closed(1, 3)} and {@code Range.greaterThan(4)},
     * this might return {@code " [1..3](4..+∞)}"}.
     */
    @Override
    String toString();
}
